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PloS One 2021Retinal oximetry is a technique based on spectrophotometry where images are analyzed with software capable of calculating vessel oxygen saturation and vessel diameter....
PURPOSE
Retinal oximetry is a technique based on spectrophotometry where images are analyzed with software capable of calculating vessel oxygen saturation and vessel diameter. In this study, the effect of automation of measurements of retinal vessel oxygen saturation and vessel diameter is explored.
METHODS
Until now, operators have had to choose each vessel segment to be measured explicitly. A new, automatic version of the software automatically selects the vessels once the operator defines a measurement area. Five operators analyzed image pairs from the right eye of 23 healthy subjects with semiautomated retinal oximetry analysis software, Oxymap Analyzer (v2.5.1), and an automated version (v3.0). Inter- and intra-operator variability was investigated using the intraclass correlation coefficient (ICC) between oxygen saturation measurements of vessel segments in the same area of the retina.
RESULTS
For semiautomated saturation measurements, the inter-rater ICC was 0.80 for arterioles and venules. For automated saturation measurements, the inter-rater ICC was 0.97 for arterioles and 0.96 for venules. For semiautomated diameter measurements, the inter-rater ICC was 0.71 for arterioles and venules. For automated diameter measurements the inter-rater ICC was 0.97 for arterioles and 0.95 for venules. The inter-rater ICCs were different (p < 0.01) between the semiautomated and automated version in all instances.
CONCLUSION
Automated measurements of retinal oximetry values are more repeatable compared to measurements where vessels are selected manually.
Topics: Adult; Automation; Humans; Oximetry; Oxygen; Reproducibility of Results; Retinal Vessels; Software; Venules; Young Adult
PubMed: 34914738
DOI: 10.1371/journal.pone.0260120 -
Sensors (Basel, Switzerland) Nov 2023Obstructive Sleep Apnea (OSA) is a respiratory disorder characterized by frequent breathing pauses during sleep. The apnea-hypopnea index is a measure used to assess the... (Review)
Review
Obstructive Sleep Apnea (OSA) is a respiratory disorder characterized by frequent breathing pauses during sleep. The apnea-hypopnea index is a measure used to assess the severity of sleep apnea and the hourly rate of respiratory events. Despite numerous commercial devices available for apnea diagnosis and early detection, accessibility remains challenging for the general population, leading to lengthy wait times in sleep clinics. Consequently, research on monitoring and predicting OSA has surged. This comprehensive paper reviews devices, emphasizing distinctions among representative apnea devices and technologies for home detection of OSA. The collected articles are analyzed to present a clear discussion. Each article is evaluated according to diagnostic elements, the implemented automation level, and the derived level of evidence and quality rating. The findings indicate that the critical variables for monitoring sleep behavior include oxygen saturation (oximetry), body position, respiratory effort, and respiratory flow. Also, the prevalent trend is the development of level IV devices, measuring one or two signals and supported by prediction software. Noteworthy methods showcasing optimal results involve neural networks, deep learning, and regression modeling, achieving an accuracy of approximately 99%.
Topics: Humans; Polysomnography; Sleep Apnea, Obstructive; Sleep; Sleep Apnea Syndromes; Oximetry
PubMed: 38067885
DOI: 10.3390/s23239512 -
Physiological Reviews Jan 1960
Topics: Oximetry
PubMed: 14427276
DOI: 10.1152/physrev.1960.40.1.1 -
Archives of Disease in Childhood Aug 2016Do newborns, children and adolescents up to 19 years have lower mortality rates, lower morbidity and shorter length of stay in health facilities where pulse oximeters... (Review)
Review
OBJECTIVE
Do newborns, children and adolescents up to 19 years have lower mortality rates, lower morbidity and shorter length of stay in health facilities where pulse oximeters are used to inform diagnosis and treatment (excluding surgical care) compared with health facilities where pulse oximeters are not used?
DESIGN
Studies were obtained for this systematic literature review by systematically searching the Database of Abstracts of Reviews of Effects, Cochrane, Medion, PubMed, Web of Science, Embase, Global Health, CINAHL, WHO Global Health Library, international health organisation and NGO websites, and study references.
PATIENTS
Children 0-19 years presenting for the first time to hospitals, emergency departments or primary care facilities.
INTERVENTIONS
Included studies compared outcomes where pulse oximeters were used for diagnosis and/or management, with outcomes where pulse oximeters were not used.
MAIN OUTCOME MEASURES
mortality, morbidity, length of stay, and treatment and management changes.
RESULTS
The evidence is low quality and hypoxaemia definitions varied across studies, but the evidence suggests pulse oximeter use with children can reduce mortality rates (when combined with improved oxygen administration) and length of emergency department stay, increase admission of children with previously unrecognised hypoxaemia, and change physicians' decisions on illness severity, diagnosis and treatment. Pulse oximeter use generally increased resource utilisation.
CONCLUSIONS
As international organisations are investing in programmes to increase pulse oximeter use in low-income settings, more research is needed on the optimal use of pulse oximeters (eg, appropriate oxygen saturation thresholds), and how pulse oximeter use affects referral and admission rates, length of stay, resource utilisation and health outcomes.
Topics: Adolescent; Child; Child, Preschool; Emergency Service, Hospital; Humans; Hypoxia; Infant; Infant, Newborn; Length of Stay; Oximetry; Primary Health Care; Treatment Outcome
PubMed: 26699537
DOI: 10.1136/archdischild-2015-309638 -
Anaesthesia May 2013
Topics: Female; Hemoglobinometry; Humans; Oximetry; Pregnancy
PubMed: 23573860
DOI: 10.1111/anae.12246 -
Journal of Applied Physiology... Jan 2016In 1875, Paul Bert linked high altitude danger to the low partial pressure of oxygen when 2 of 3 French balloonists died euphorically at about 8,600 m altitude. World... (Review)
Review
In 1875, Paul Bert linked high altitude danger to the low partial pressure of oxygen when 2 of 3 French balloonists died euphorically at about 8,600 m altitude. World War I fatal crashes of high altitude fighter pilots led to a century of efforts to use oximetry to warn pilots. The carotid body, discovered in 1932 to be the hypoxia detector, led to most current physiologic understanding of the body's respiratory responses to hypoxia and CO2. The author describes some of his UCSF group's work: In 1963, we reported both the brain's ventral medullary near-surface CO2 (and pH) chemosensors and the role of cerebrospinal fluid in acclimatization to altitude. In 1966, we reported the effect of altitude on cerebral blood flow and later the changes of carotid body sensitivity at altitude and the differences in natives of high altitude. In 1973, pulse oximetry was invented when Japanese biophysicist Takuo Aoyagi read and applied to pulses a largely forgotten 35-year-old discovery by English medical student J. R. Squire of a method of computing oxygen saturation from red and infrared light passing through both perfused and blanched tissue.
Topics: Acclimatization; Altitude; Animals; Humans; Oximetry; Oxygen; Partial Pressure
PubMed: 26251514
DOI: 10.1152/japplphysiol.00476.2015 -
Anales de Pediatria (Barcelona, Spain :... Sep 2003Noninvasive methods of monitoring are crucial in the management of intensive care patients, especially in the pediatric field. Pulse oxymetry measures arterial oxygen... (Review)
Review
Noninvasive methods of monitoring are crucial in the management of intensive care patients, especially in the pediatric field. Pulse oxymetry measures arterial oxygen saturation in severely ill patients, allows oxygen requirements to be adjusted to the patient, reduces invasive gasometric studies and achieves continuous monitoring of the critically ill child. Motion and deficient tissular perfusion reduce the accuracy of the measured values, but more sophisticated pulse oximeters are more effective in preventing these artifacts. Capnometers are an excellent method of measuring end-tidal CO2 values in real time in intubated patients. Capnography produces a graphic curve of end-tidal CO2 while capnometry provides a numerical representation of this concentration. This technique is highly useful in the continuous monitoring of various respiratory problems and situations such as weaning or checking the correct placement of endotracheal cannulas.
Topics: Blood Gas Monitoring, Transcutaneous; Capnography; Carbon Dioxide; Child; Humans; Hyperventilation; Oximetry; Respiratory Insufficiency
PubMed: 14596270
DOI: 10.1016/s1695-4033(03)78176-4 -
The Cochrane Database of Systematic... Oct 2014The use of conventional cardiotocographic (CTG) monitoring of fetal well-being during labour is associated with an increased caesarean section rate, compared with... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
The use of conventional cardiotocographic (CTG) monitoring of fetal well-being during labour is associated with an increased caesarean section rate, compared with intermittent auscultation of the fetal heart rate, resulting in a reduction in neonatal seizures, although no differences in other neonatal outcomes. To improve the sensitivity of this test and therefore reduce the number of caesarean sections performed for nonreassuring fetal status, several additional measures of evaluating fetal well-being have been considered. These have demonstrated some effect on reducing caesarean section rates, for example, fetal scalp blood sampling for pH estimation/lactate measurement. The adaptation of pulse oximetry for use in the unborn fetus could potentially contribute to improved evaluation during labour and therefore lead to a reduction in caesarean sections for nonreassuring fetal status, without any change in neonatal outcomes.
OBJECTIVES
To compare the effectiveness and safety of fetal intrapartum pulse oximetry with other surveillance techniques.
SEARCH METHODS
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 May 2014), contacted experts in the field and searched reference lists of retrieved studies. In previous versions of this review, we performed additional searches of MEDLINE, Embase and Current Contents. These searches were discontinued for this review update, as they consistently failed to identify any trials that were not shown in the Cochrane Pregnancy and Childbirth Group's Trials Register.
SELECTION CRITERIA
All published and unpublished randomised controlled trials that compared maternal and fetal outcomes when fetal pulse oximetry was used in labour, (i) with or without concurrent use of conventional fetal surveillance, that is, cardiotocography (CTG), compared with using CTG alone or (ii) with or without concurrent use of both CTG and other method(s) of fetal surveillance, such as fetal electrocardiography (ECG) plus CTG.
DATA COLLECTION AND ANALYSIS
At least two independent review authors performed data extraction. We sought additional information from the investigators of three of the reported trials.
MAIN RESULTS
We included seven published trials: six comparing fetal pulse oximetry and CTG with CTG alone (or when fetal pulse oximetry values were blinded) and one comparing fetal pulse oximetry plus CTG with fetal ECG plus CTG. The published trials, with some unpublished data, were at high risk of bias in terms of the impractical nature of blinding participants and clinicians, as well as high risk or unclear risk of bias for outcome assessor for all but one report. Selection bias, attrition bias, reporting bias and other sources of bias were of low or unclear risk. The trials reported on a total of 8013 pregnancies. Differing entry criteria necessitated separate analyses, rather than meta-analysis of all trials.Systematic review of four trials from 34 weeks not requiring fetal blood sampling (FBS) prior to study entry showed no evidence of differences in the overall caesarean section rate between those monitored with fetal oximetry and those not monitored with fetal pulse oximetry or for whom the fetal pulse oximetry results were masked (average risk ratio (RR) 0.99 using random-effects, 95% confidence intervals (CI) 0.86 to 1.13, n = 4008, I² = 45%). There was evidence of a higher risk of caesarean section in the group with fetal oximetry plus CTG than in the group with fetal ECG plus CTG (one study, n = 180, RR 1.56, 95% CI 1.06 to 2.29). Neonatal seizures and neonatal encephalopathy were rare in both groups. No studies reported details of long-term disability.There was evidence of a decrease in caesarean section for nonreassuring fetal status in the fetal pulse oximetry plus CTG group compared to the CTG group, gestation from 34 weeks (average RR (random-effects) 0.65, 95% CI 0.46 to 0.90, n = 4008, I² = 63%). There was no evidence of differences between groups in caesarean section for dystocia, although the overall incidence rates varied between the trials.
AUTHORS' CONCLUSIONS
The addition of fetal pulse oximetry does not reduce overall caesarean section rates. One study found a higher caesarean section rate in the group monitored with fetal pulse oximetry plus CTG, compared with fetal ECG plus CTG. The data provide limited support for the use of fetal pulse oximetry when used in the presence of a nonreassuring CTG, to reduce caesarean section for nonreassuring fetal status. A better method than pulse oximetry is required to enhance the overall evaluation of fetal well-being in labour.
Topics: Cardiotocography; Cesarean Section; Delivery, Obstetric; Female; Fetal Monitoring; Humans; Oximetry; Pregnancy; Randomized Controlled Trials as Topic
PubMed: 25287809
DOI: 10.1002/14651858.CD004075.pub4 -
Journal of Clinical Sleep Medicine :... Oct 2011Guidance is needed to help clinicians decide which out-of-center (OOC) testing devices are appropriate for diagnosing obstructive sleep apnea (OSA). A new classification... (Review)
Review
Guidance is needed to help clinicians decide which out-of-center (OOC) testing devices are appropriate for diagnosing obstructive sleep apnea (OSA). A new classification system that details the type of signals measured by these devices is presented. This proposed system categorizes OOC devices based on measurements of Sleep, Cardiovascular, Oximetry, Position, Effort, and Respiratory (SCOPER) parameters.Criteria for evaluating the devices are also presented, which were generated from chosen pre-test and post-test probabilities. These criteria state that in patients with a high pretest probability of having OSA, the OOC testing device has a positive likelihood ratio (LR+) of 5 or greater coinciding with an in-lab-polysomnography (PSG)-generated apnea hypopnea index (AHI) ≥ 5, and an adequate sensitivity (at least 0.825).Since oximetry is a mandatory signal for scoring AHI using PSG, devices that do not incorporate oximetry were excluded. English peer-reviewed literature on FDA-approved devices utilizing more than 1 signal was reviewed according to the above criteria for 6 questions. These questions specifically addressed the adequacy of different respiratory and effort sensors and combinations thereof to diagnose OSA. In summary, the literature is currently inadequate to state with confidence that a thermistor alone without any effort sensor is adequate to diagnose OSA; if a thermal sensing device is used as the only measure of respiration, 2 effort belts are required as part of the montage and piezoelectric belts are acceptable in this context; nasal pressure can be an adequate measurement of respiration with no effort measure with the caveat that this may be device specific; nasal pressure may be used in combination with either 2 piezoelectric or respiratory inductance plethysmographic (RIP) belts (but not 1 piezoelectric belt); and there is insufficient evidence to state that both nasal pressure and thermistor are required to adequately diagnose OSA. With respect to alternative devices for diagnosing OSA, the data indicate that peripheral arterial tonometry (PAT) devices are adequate for the proposed use; the device based on cardiac signals shows promise, but more study is required as it has not been tested in the home setting; for the device based on end-tidal CO(2) (ETCO(2)), it appears to be adequate for a hospital population; and for devices utilizing acoustic signals, the data are insufficient to determine whether the use of acoustic signals with other signals as a substitute for airflow is adequate to diagnose OSA.Standardized research is needed on OOC devices that report LR+ at the appropriate AHI (≥ 5) and scored according to the recommended definitions, while using appropriate research reporting and methodology to minimize bias.
Topics: Equipment Design; Humans; Monitoring, Ambulatory; Oximetry; Plethysmography, Impedance; Predictive Value of Tests; Respiratory Function Tests; Sleep Apnea, Obstructive; Transducers, Pressure
PubMed: 22003351
DOI: 10.5664/JCSM.1328 -
British Journal of Anaesthesia Jun 2014The nasal ala is an attractive site for pulse oximetry because of perfusion by branches of the external and internal carotid arteries. We evaluated the accuracy of a...
BACKGROUND
The nasal ala is an attractive site for pulse oximetry because of perfusion by branches of the external and internal carotid arteries. We evaluated the accuracy of a novel pulse oximetry sensor custom designed for the nasal ala.
METHODS
After IRB approval, healthy non-smoking subjects [n=12; aged 28 (23-41) yr; 6M/6F] breathed hypoxic mixtures of fresh gas by a facemask to achieve oxyhaemoglobin saturations of 70-100% measured by traditional co-oximetry from radial artery samples. Concurrent alar and finger pulse oximetry values were measured using probes designed for these sites. Data were analysed using the Bland-Altman method for multiple observations per subject.
RESULTS
Bias, precision, and accuracy root mean square error (ARMS) over a range of 70-100% were significantly better for the alar probe compared with a standard finger probe. The mean bias for the alar and finger probes was 0.73% and 1.90% (P<0.001), respectively, with corresponding precision values of 1.65 and 1.83 (P=0.015) and ARMS values of 1.78% and 2.72% (P=0.047). The coefficients of determination were 0.96 and 0.96 for the alar and finger probes, respectively. The within/between-subject variation for the alar and finger probes were 1.14/1.57% and 1.87/1.47%, respectively. The limits of agreement were 3.96/-2.50% and 5.48/-1.68% for the alar and finger probes, respectively.
CONCLUSIONS
Nasal alar pulse oximetry is feasible and demonstrates accurate pulse oximetry values over a range of 70-100%. The alar probe demonstrated greater accuracy compared with a conventional finger pulse oximeter.
Topics: Adult; Feasibility Studies; Female; Humans; Male; Nasal Cartilages; Oximetry; Reproducibility of Results; Young Adult
PubMed: 24736392
DOI: 10.1093/bja/aeu095